Limesurvey creates directories such as
tmp/assets/4aa930f2/scripts
(which I presume is a file cache).

The directories have permissions '777' and the files have permissions 777 (writable by world)

For security I would like the permissions to be 755 and 644 (writable by owner only)

Is there a config setting where I can set the file permissions of newly created dirs and files?
I have tried adding this to config.php:
'''
/* see www.yiiframework.com/doc/api/2.0/yii-caching-filecache */
'cache' =>[
'dirMode'=>755,
'fileMode'=>644
],
'''
but got an error message, something like "config item 'cache' is read only".